base64-string-to-usb8-array

Arguments:
string &key start end output

This function converts the base64 string which is the value of
string to an (unsigned-byte 8) array (with the
six bits of the first converted character of
string becoming the most significant six bit of
the first element of the result array and so on). Two values are
returned: the array and the number of bytes added to the returned
array.

The start and end keyword argument specify the portion of the input
string to convert. If unspecified, the whole string is used.

The output keyword argument allows specification of a (unsigned-byte
8) array in which to place the result. The result whill be written
into the output array starting at index 0. The number of bytes written
is the second returned value. If the output array is not large enough
to hold the result or if output is unspecified or nil, a new array is
created abd returned.